Outline

Objective: The management of deep-seated cerebral cavernous malformations (CCMs, synonyms: cavernomas, angiographyically occult vascular malformations, AOVMs) is still controversial. Although surgery remains the treatment of choice in patients with recurrent hemorrhage, CCMs located in the brain stem are not eligible for resection in many cases due to high procedure-related morbidity. The aim of this retrospective study is to determine the long-term outcome of stereotactic radiosurgery (SRS) for brain stem CCMs.

Methods: Between December 1992 and March 2008, 14 consecutively admitted patients (m:f = 7:7) harboring brainstem CCMs underwent stereotactic radiosurgery using an adapted linear accelerator (LINAC-RS). Pre-treatment imaging showed no associated developmental venous angiomas (DVAs) in any of our patients. All patients presented with prior symptomatic hemorrhage. A median follow-up of 6.8 years (range: 1.7 - 16.5) could be obtained in all but one patient (93%). SRS was performed by the application of a median single dose of 13.5 Gray (Gy) (range: 11 - 18 Gy) to the surface of the CCMs (median volume 1.6 ml, range: 0.4 - 4.3 ml).

Results: One of 13 patients (7.7%) had to undergo additional microsurgery due to rebleeding 9 months after radiosurgery. The corresponding ratio of patient-years/bleeding-frequency was 88.4 y / 1 (post-RS). The neurological outcome of the remaining 12 patients (92.3%) was improved in 7 patients (53.8%), remained unchanged in 4 (33.3%) and worsened in one patient (7.7%). Adverse radiation effects (ARE, defined by perilesional hyperintensity on T2-weighted MR images) were revealed in five patients (38.5%), leading to transient neurological deficits in 3 patients (23.1%).

Conclusions: Our results support the role of SRS as an efficient and safe treatment to reduce the annual hemorrhage rate in patients suffering from brain stem CCMs not eligible to microsurgery. Compared with radiosurgery for AVM, the intervention-related morbidity is higher.